Investigations into the relative abundance of Intersexual pigs (Sus
sp.) in the Republic of Vanuatu.

This article was originally published in "Science in New Guinea" vol.
22(3); 1997

Abstract

The existence and great abundance of a unique form of pig intersexuality was
verified on the northernmost islands of Vanuatu.

Morphological examinations were conducted on 54 pigs from the islands of Malo, Ambae,
and Aore. Through blood analysis, estradiol and testosterone levels were derived.
Subsequent comparisons of the estradiol/testosterone ratio yielded results consistent with
"maleness". Fifty-one dental and mandibular measurements of the Vanuatu Sus. sp.
specimens plotted within the feral swine target group.

Behaviorally, the Vanuatu intersex pig exhibits periods of aggressiveness that
generally coincide with a sow in heat. When encountered in the "bush", the
naravé (local name for the intersexual pig) is a stronger and more aggressive adversary
than the "normal" native wild pig. Six gross dissections yielded totally male
internal sex organs. Four separate graduations or phases of the intersexual condition are
described according to their external genitalia. The phases of intersexuality appeared to
be an inherited trait. Certain sows (called falé-ravé) are known intersex producers and
20% of their offspring will be intersexual.